Bransfield Strait, a narrow active rift with three submarine basins, separates the South Shetland
Islands from northern Antarctic Peninsula. Volcanism in Bransfield Strait commenced prior to 0.75 Ma and
continues, with recent subaerial eruptions at Deception, Bridgeman and Penguin islands, submarine
hydrothermal activity and numerous young basaltic seamounts located along the rift axis. Gravity cores were
collected from five locations within the central Bransfield basin. Diatomaceous mud interbedded with
terrigenous detritus and discrete ash layers up to 10 cm thick are the commonest sediment types in all the
cores. The major element compositions of glass shards within the ash layers are, apart from the uppermost
layer, compositionally similar to pyroclastic units preserved on Deception Island, a young (<0.75 Ma) active
stratovolcano. The uppermost ash layer cannot be closely matched compositionally to any known source in
the Antarctic–Scotia Sea–southern South America region. Its presence indicates that a volcanic centre other
than Deception Island contributed ash to the Bransfield basin. Based on the shallow stratigraphical position
of the compositionally distinctive ash layer, only a few decimetres beneath the seafloor, its source volcano
was probably active in historical times (<few hundred years).